To perform this quenching and/or this homogenization, one skilled in the art is often led to use a specific arrangement of internal parts that are often complex, comprising supplying the quenching fluid, as homogeneous as possible, into the reactor section. U.S. Pat. No. 6,180,068 describes in particular an arrangement of a mixing system for a gaseous phase and a liquid phase for a reactor working with descending current fluids and including, above a plate (15) for separating the reactor into two parts, separate means for supplying gas and liquid, each means equipped with means for making each fluid rotate with the help of a deflector and a central inlet of the fluid mixture into the part of the system located below separation plate (15). Such a system is complex because it requires the installation of numerous internal parts without providing for efficient mixing of the two phases, gas and liquid. The fluid mixture exits this system through an annular section below plate (15) directly, without formation of a retention of fluids and thus without improving the quality of the mixture produced in the upper part of this system above plate (15) and entering into the lower part of said system through a central opening. These choices imply a necessarily reduced duct cross section. Indeed, the duct cross section must be significantly smaller than that of the box if it is not desired to reduce too much the volume of the box needed for the mixture. The use of a small duct section implies a large material loss at the box outlet.
According to the teaching of U.S. Pat. No. 5,462,719 many internal parts are used such as blades, fins, baffles, or deflectors to make the gaseous and liquid fluids rotate. Contrary to the teaching of the more recent patent cited above, the system used does not comprise separately starting the gaseous fluid and the liquid fluid to rotate, but that of the mixture of the two. However, as in the more recent patent cited above, this startup of rotation is performed in a part located above a separation plate (20) and includes supplying the mixture formed in a part located below said separation plate (20) with a mixture outlet made by numerous holes distributed on the periphery of the lower part of this mixing system. The major drawbacks of this type of system, besides the quality of the mixture which is often more or less good, are the bulkiness (space taken up in the reactor), the complexity of design and use, and the material loss.
U.S. Pat. No. 5,837,208 describes a mixing system located below a separation plate (16) in which the gaseous and liquid fluids enter together into a mixing chamber (20) located below said separation plate (16) through a spiliway system (26-27) located on the plate and making them rotate. The fluid mixture formed in said mixing chamber exits through a central opening located at a level lower than that of its entry into said box. This opening comprises walls (8) that force a retention of the fluid in said box and promote mixing among the various phases. One of the major drawbacks of this type of system is, in particular, due to the significant risk of a direct exit of a non-negligible portion of the fluid mixture, which does not sufficiently rotate in said box and exits directly by the central opening. Moreover, this choice implies a necessarily reduced duct cross section. Indeed, the duct cross section must be significantly smaller than that of the box if it is desired not to reduce too much the volume of the box needed for the mixture. The use of a small duct section implies a large material loss at the box outlet.
According to the technique described in U.S. Pat. Nos. 5,403,560 and 5,543,346, the system proposed for performing a quenching and mixing function comprises an upper part in which the fluids are made to rotate with the help of a helicoid screw and exit in a lower part located approximately at the center of the system. This relatively complex unit also includes a series of fins whose function is to create significant turbulence in the fluids, which further complicates the device. This system implies a necessarily reduced duct cross section. Indeed, the duct cross section must be significantly smaller than that of the box if it is desired not to reduce too much the volume of the box needed for the mixture. The use of a small duct section implies a large material loss at the box outlet.
In many systems described in the prior art, the inlets and outlets are generally very numerous as can be seen, in particular, from descriptions and patents U.S. Pat. No. 5,462,719 and U.S. Pat. No. 5,567,396. It is then unlikely that a preexisting local heterogeneity at the inlet to the system could be reduced at the outlet of the system, which does not appear to provide for a sufficient mixing with all of the fluid(s) circulating in the system.